def conflict(state,nextX):
    nextY = len(state)
    for i in range(nextY):
        if abs(state[i]) - nextX in (0, nextY-i):
            return True

    return False

def queens(num=8, state=()):
    for pos in range(num):
        if not conflict(state,pos):
            if len(state) == num - 1:
                yield(pos,)
            else:
                for result in queens(num, state+(pos,)):
                    yield (pos,)+result

def pretty_print(solution):
    def line(pos,length=len(solution)):
        return '.' * pos + 'X' + '.' * (length - pos -1)
    for pos in solution:
        print line(pos)

import random

pretty_print(random.choice(list(queens(8))))
